Author Topic: Bass acoustic issues  (Read 13843 times)

Offline jimbones

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Bass acoustic issues
« on: December 08, 2014, 08:23:56 AM »
Professor,

See my room layout attached :-P
Modwright LS100, Wells Audio Innamorata Pwr, VPI Classic II/BenzMicro Glider, Lambda Legend OB Speakers,  Auralic Vega DAC, Emotiva ERC-3,Lumin D1, MIT, WireWorld, Wywires, Shunyata, PS Audio, TWL

Offline richidoo

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Re: Bass acoustic issues
« Reply #1 on: December 08, 2014, 08:51:45 AM »
I started a new thread for this.

See previous posts related to this thread, starting here:

http://www.audionervosa.com/index.php?topic=5284.msg66764#msg66764

Sorry I can't move them into this thread.

Offline richidoo

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Re: Bass acoustic issues
« Reply #2 on: December 08, 2014, 08:52:50 AM »
You are a visio master  8)

Jim, what is the actual problem you are having with the bass?

« Last Edit: December 08, 2014, 09:16:16 AM by richidoo »

Offline richidoo

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Re: Bass acoustic issues
« Reply #3 on: December 08, 2014, 09:13:20 AM »

Offline jimbones

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Re: Bass acoustic issues
« Reply #4 on: December 08, 2014, 09:23:20 AM »
Boomy. I haven't measured it yet but if I had to guess around 45-50 hz. I will have to update the visio file it is a bit outdated.
Modwright LS100, Wells Audio Innamorata Pwr, VPI Classic II/BenzMicro Glider, Lambda Legend OB Speakers,  Auralic Vega DAC, Emotiva ERC-3,Lumin D1, MIT, WireWorld, Wywires, Shunyata, PS Audio, TWL

Offline jimbones

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Re: Bass acoustic issues
« Reply #5 on: December 08, 2014, 09:32:36 AM »
updated visio
Modwright LS100, Wells Audio Innamorata Pwr, VPI Classic II/BenzMicro Glider, Lambda Legend OB Speakers,  Auralic Vega DAC, Emotiva ERC-3,Lumin D1, MIT, WireWorld, Wywires, Shunyata, PS Audio, TWL

Offline tmazz

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Re: Bass acoustic issues
« Reply #6 on: December 08, 2014, 01:00:55 PM »
Jim, have you ever thought of  blocking off that hallway the leads back to the stairs? Between the hall and the turn around up the stairs I wounder if it isn't forming some kind of resonant cavity. You could try with just a scrap piece of plywood or sheetrock and if it helps put in a permanent door.
Remember, it's all about the music........

Nola Boxers
Sunfire True SW Super Jr (2)
McIntosh MC 275
ARC SP-9
VPI HW-19 Mk IV/SDS/SME IV/Sumiko Blue Pt. Special
Pro-Ject Pre Box S2 DAC/Bluesound Node/Pioneer DV 563A
DigiBuss/TWL PC/MIT Cable

Offline richidoo

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Re: Bass acoustic issues
« Reply #7 on: December 08, 2014, 02:09:01 PM »
That long hall is the stairway, right? The room width and the hallway are both 22 feet, which is 25Hz fundamental, 50Hz 2nd harmonic. So the hallway could have something to do with it, especially since your ears are parked right at the halfway point, max amplitude of the resonance.  See attached picture of modecalc mode prediction. 

You could improve your S/N in the midrange by making a fake wall between the side room and your listening area. But you get used to it, it's not a huge deal unless you are really picky about clarity in midrange.

Is the visio all concrete walls or is there other rooms? Finished ceiling? Insulated? Height?

I like the position of the sub in the previous visio, closer to you. The sub should always be closer to you than the main speakers so that you can time align them with the sub delay (phase) control. Out of alignment sub will make the bass sound blurred.

Depending on how low you crossover a good place for the sub might be right behind your chair.  :shock:  You increase the S/N ratio a lot having it close. The reflections are delayed and much quieter which cleans it up a lot. You can turn it way down in volume so it won't generate as strong modes in the room, and it is closer than the mains so you can delay it to align perfectly with the mains. And it is still out of the way. If you cross it above 80Hz then it must be near the speakers because it starts to locate for most people at 100Hz.  You may want smaller 8" separate stereo subs at the speakers for >50Hz, and a big sub closeup for <50hz.

See if you can do a FR sweep with that omnimic? With both speakers playing and the sub turned on... as a baseline, or is it bass line?

Offline jimbones

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Re: Bass acoustic issues
« Reply #8 on: December 08, 2014, 03:32:47 PM »
Ok so there's a lot of info and I'll try to handle a few bites at a time. The hallway leads to a stair that isn't shown. It is a 180 degree turn and the up the stairs. I can wall that hallway off if I have to, maybe put a solid door.

The walls are sheet rock with knotty pine on the bottom half. The ceiling is 2x2 drop with Roxul between then joists and diffusors in selected areas. BTW I do have a walled off section (Plywood) just above the record cabinet that seperates the 2 rooms.  More to come.  :lol:
Modwright LS100, Wells Audio Innamorata Pwr, VPI Classic II/BenzMicro Glider, Lambda Legend OB Speakers,  Auralic Vega DAC, Emotiva ERC-3,Lumin D1, MIT, WireWorld, Wywires, Shunyata, PS Audio, TWL

Offline jimbones

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Re: Bass acoustic issues
« Reply #9 on: December 08, 2014, 03:35:12 PM »
BTW my sub only has a phase switch and is not continuously variable.  :( ceiling height is NOT 8 ft I'll get exact measurements
Modwright LS100, Wells Audio Innamorata Pwr, VPI Classic II/BenzMicro Glider, Lambda Legend OB Speakers,  Auralic Vega DAC, Emotiva ERC-3,Lumin D1, MIT, WireWorld, Wywires, Shunyata, PS Audio, TWL

Offline richidoo

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Re: Bass acoustic issues
« Reply #10 on: December 08, 2014, 05:38:09 PM »
Ceiling height is not critical. The height to the hard plane above the joists is what matters. The drop ceiling is invisible to LF.

Low bass will move through sheetrock walls pretty easily but it will reflect on concrete. Mid and upper bass has varying reflectivity from stick walls.

The sub position and phase stuff is pretty much a different topic. Let's see about the acoustics first.

Offline jimbones

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Re: Bass acoustic issues
« Reply #11 on: December 09, 2014, 06:14:43 AM »
One other idea since it is quick and wont cost me anything is to put a bass trap in that ling hallway and see if it changes anything. Getting more bass traps can't hurt.
Modwright LS100, Wells Audio Innamorata Pwr, VPI Classic II/BenzMicro Glider, Lambda Legend OB Speakers,  Auralic Vega DAC, Emotiva ERC-3,Lumin D1, MIT, WireWorld, Wywires, Shunyata, PS Audio, TWL

Offline tmazz

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Re: Bass acoustic issues
« Reply #12 on: December 09, 2014, 06:39:13 AM »
I want to be there when you tell Maria that the final step to prefecting you speaker design will be to buy a new house to put them in.   :duh

(It will be easy to spot me. I'll be the one standing off to the side with the First Aid kit.  :rofl: :rofl:)
Remember, it's all about the music........

Nola Boxers
Sunfire True SW Super Jr (2)
McIntosh MC 275
ARC SP-9
VPI HW-19 Mk IV/SDS/SME IV/Sumiko Blue Pt. Special
Pro-Ject Pre Box S2 DAC/Bluesound Node/Pioneer DV 563A
DigiBuss/TWL PC/MIT Cable

Offline jimbones

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Re: Bass acoustic issues
« Reply #13 on: December 09, 2014, 07:25:34 AM »
ha ha. You're not kidding. I am "considering" the idea of building a dipole bass unit to go down to 80 hz, prefer  without equalization. Even at 80 hz it would be quite large I am thinking. Might have to reconsider. BTW if I did move to another house yes it would have to be "audiophile friendly"
Modwright LS100, Wells Audio Innamorata Pwr, VPI Classic II/BenzMicro Glider, Lambda Legend OB Speakers,  Auralic Vega DAC, Emotiva ERC-3,Lumin D1, MIT, WireWorld, Wywires, Shunyata, PS Audio, TWL

Offline richidoo

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Re: Bass acoustic issues
« Reply #14 on: December 09, 2014, 08:55:51 AM »
Dipole does alleviate a lot of bass problems. When I used Quads the bass was very clean.  I would like to try dipole again.

Rythmik/GR is probably the best system for low distortion OB bass. It can play low and loud and clear with slam, like an EQ'd low Q driver.

Without feedback or EQ you will need high Q drivers to get LF extension and SPL, and that requires sacrificing some detail and control, so it pairs best with warmer musical type midrange driver. Hawthorne and AE make good quality OB drivers for passive crossover with no EQ.
« Last Edit: December 09, 2014, 09:00:31 AM by richidoo »